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How much of your deficit should come from exercise?

How much of your deficit should come from exercise?

You picked a daily calorie target in Burnie. Now the real question is how to split it between food and exercise. Food cuts carry most of the deficit, and exercise adds a smaller, honest slice. Here is the maths and how to set your own split.

1 Aug 2026 · Burnie Academy
calorie-deficit exercise food-vs-exercise weight-loss-maths

You picked a daily calorie target in Burnie. Maybe 500 kcal under your burn. Good. Now comes the real question. How much should come from eating less, and how much from moving more? Most people guess wrong. They think one long walk pays for the extra roti. It does not. Let us do the honest maths.

The honest split for a 500 kcal deficit

130-250

Say your target is a 500 kcal deficit today. A 30-minute brisk walk burns about 133 kcal for a 70 kg adult. So that walk chips in about 133 of your 500. That is about one quarter of the gap. The other three quarters, about 370 kcal, must come from food. That 370 kcal is roughly four home rotis. Each roti is about 85 kcal. Food carries the bigger share. Exercise adds a smaller, honest slice.

Three ways to build a 500 kcal deficit

Food only - cut about 500 kcal
Like leaving six home rotis off your day (6 x 85). No time cost, but a big hunger jump.
Exercise only - walking
About 3.75 hours of brisk walking (500 divided by 133). Almost no one keeps this up every day.
Exercise only - running
About 42 minutes of running at 6 mph (500 divided by 360). Tough on the joints if you are heavy.
Smart split - food plus walk
Cut about 370 kcal from food (roughly four rotis) plus one 30-min walk (about 130 kcal). Exercise carries about one quarter.

If I train hard enough, exercise can carry my whole deficit.

mostly false

mostly false

The maths is brutal. A 70 kg adult burns about 133 kcal in a 30-minute walk. To get all 500 kcal from walking, you would walk about 3.75 hours each day. Even running at 6 mph burns about 360 kcal in 30 minutes. So you would still need about 42 minutes of running daily. Then the body partly takes it back. A 2023 review checked many studies. It found about 67% saw people drop their other daily movement when they began structured exercise. So exercise alone rarely carries the whole deficit. Food has to do most of the work.

How to set your own split

The bottom line

Food moves the deficit number faster. Exercise is the kind bonus that guards your muscle, heart, and mood. Let food carry most of the gap, and let a daily walk add an honest slice. Split it your way - and let Burnie do the maths.

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